This invention relates to very low creep, ultra high modulus, low shrink, high tenacity polyolefin fiber having good strength retention at high temperatures and the method to produce such fiber. U.S. Pat. No. 4,413,110, herein incorporated by reference, in toto, discloses a prior art fiber and process which could be a precursor process and fiber to be poststretched by the method of this invention to create the fiber of this invention.
Although a tensile strength value of 4.7 GPa (55 g/d) has been reported for a single crystal fibril grown on the surface of a revolving drum from a dilute solution of ultra high molecular weight polyethylene, and separately, a tensile modulus value of 220 GPa (2600 g/d) for single crystal mats of polyethylene grown from dilute solution and subsequently stretched in two stages to about 250 times original; the combination of ultra high modulus and high tenacity with very low creep, low shrinkage and much improved high temperature performance has never before been achieved, especially in a multifilament, solution spun, continuous fiber by a commercially, economically feasible method.